£18m Glen is sum signing

Benitez splashed out almost £18m taking the England defender from Portsmouth to beat off competition from Chelsea.

Johnson will complete his switch when he ­returns from holiday – but Benitez said he had to go the extra mile to finally get his man.

He said: “Sometimes you have to spend a little bit more.

“You can’t compete in the top four of the ­Premier League ­unless you spend some money. We were looking for a player of quality and also somebody who is British because of the new Champions League rules.

“Glen Johnson fits both categories.”

The fact Benitez has been able to make his first summer signing will help fend off claims the club are in financial trouble.

Kop Holdings, the club’s parent company, posted a £42.6m loss in the year to August 2008 but ­concerns over the £350m loan taken out by ­American owners Tom Hicks and George Gillett have lessened with a re-financing agreement with RBS now close to being sealed.

Benitez is confident he will make other ­signings – but the main focus at present is making sure he can hang on to the likes of Xabi Alonso, Alvaro Arbeloa and Javier Mascherano, who have all been linked with moves to Real Madrid and Barcelona.

He added: “We have a plan. We can sign one more player if necessary – but that’s without any players leaving.

“Alvaro Arbeloa has had a very good season but he has one year left on his contract.

“If he signs that will be good because we will have more competition – but if we get a good offer we will have to consider it.”

That looks set to come from Real, who are ­preparing a joint bid for the defender and Alonso.

Asked about Alonso last night, Madrid director general Jorge Valdano said: “We have possibilities there but I don’t want to say anything that will make the negotiation more difficult.

“We will wait a reasonable amount of time. A­rbeloa only has a year left on his contract with Liverpool and this gives us more possibilities. He is another option to evaluate.”